The present invention relates to methods for producing Euphorbia pulcherrima×Euphorbia cornastra interspecific hybrid plants having red bracts and non-functional small cyathia and the plants produced by the method. All publications cited in this application are herein incorporated by reference.
The field of the invention relates to horticulture, plant breeding and plant genetics.
The ornamental plant market is large and diverse and within this market there is an ever present need for new innovative products and improvements to increase customer satisfaction and interest. One popular type of plant sold in this market is the Poinsettia (Euphorbia pulcherrima). Poinsettia is well known for its colourful bracts (subtending the flowers), which are produced in a range of colours such as red, white, pink, purple and orange. Red is the most popular colour, accounting for the majority of world-wide sales.
Interspecific hybrids have been produced between Euphorbia pulcherrima (2n=28) and Euphorbia cornastra (2n=28) as described in: Kobayashi, R. Euphorbia interspecific hybrid plant, U.S. Pat. No. 6,515,200, filed Oct. 16, 2000 and Bernuetz, A. Method of producing Euphorbia interspecific hybrid plants by cutting and then culturing the hybrid embryos, United States Patent publication number 20060218679, filed Sep. 28, 2006. The plants produced from the methods outlined in the two aforementioned references, herein incorporated in their entirety, have a different appearance and some improved characteristics when compared to Euphorbia pulcherrima. For example, hybrid plants of Euphorbia pulcherrima×Euphorbia cornastra tend to have higher branching capability and smaller bract size when compared to commercially available poinsettias. Hybrid plants of Euphorbia pulcherrima×Euphorbia cornastra always have pink bracts and usually lower post-production performance when compared to the most popular poinsettia cultivars. Commercially available cultivars of Euphorbia pulcherrima×Euphorbia cornastra include the PRINCETTIA series (Bonza Botanicals, Pty Ltd, U.S. Plant Patents PP23,296; PP21,327; PP21,326; PP21,325; PP21324) and Dulce Rosa (U.S. Plant Patent PP15,849). Mutation breeding can result in varying shades of pink and the cultivar PRINCETTIA MaxWhite (U.S. Plant Patent PP23,296) has white to very faint pink bracts with a pink vein.
The commercially available Euphorbia pulcherrima×Euphorbia cornastra hybrids are almost fully male sterile (fertile anthers may occasionally be produced on some cultivars) and all are female sterile. The fact these plants are so infertile limits the ability to perform further breeding work and improvements.
Although the methods outlined in the previously mentioned references have been useful to develop commercially viable ornamental interspecific hybrid E. pulcherrima×E. cornastra plants, it has been impossible to develop an interspecific hybrid E. pulcherrima×E. cornastra plant by these methods with (a) non-functional small cyathia and (b) red flower bracts.